Adults and children living in the Great Lakes region are exposed to complex environmental contaminants including RGBs, DDE and mercury. PCBs in particular have been implicated in cognitive impairments in children. The major goal of this proposal is to determine whether low level, prenatal PCBs compromise cognitive development in the teen years. An established database of intrauterine (cord blood and placenta) PCBs, DDE, Mirex, HCB, lead, EP and hair mercury which were collected when each child from the Oswego Project was born are on file for the proposed projects existing 202 participants. In addition, the project also contains data regarding a host of behavioral measures, demographics, substance use, as well as 50+ potentially confounding variables within the analytic database. These data, along with low project attrition, enable us to assess cognitive development and impulse control as the children enter early teenage years. The current proposal is the continuation of the research from the Oswego Project and is bolstered by published and yet-to-be published data that suggest that prenatal exposure to PCBs impairs global skills, cognitive skills and behavioral impulsivity in children. [unreadable] [unreadable] Specific Aim 1) To investigate the different components of response inhibition that underlies the sustained PCB-related deficits on continuous performance and operant tasks seen at 4, 8 and 10 [unreadable] years of age. [unreadable] [unreadable] Specific Aim 2) To study (via MRI assessment) the fronto-striatal structures that mediate and the posterior structures that modify PCB-related impulsive responding. [unreadable] [unreadable] Specific Aim 3) To assess the stability of the association between prenatal PCB exposure and Global [unreadable] Intelligence (IQ) through re-assessment of IQ at 15 years of age [unreadable] [unreadable]